Ecology:
The big picture: Earth’s climate controls species distributions
- Ecology can be measured at many different levels
- individual → ecosystem → biosphere
- The environment regulates where species can be
- What regulates the environment?
- Earth is divided up into different life zones
- control the distribution of species
- climate creates life zones
- Abiotic and biotic factors determine where species can exist
What is climate?
- Climate:
- i.e. temperature, precipitation, sunlight & wind
- often 30 year averages
- Global climate depends on the amount of energy received by the sun and the amount of energy that is trapped in the system.
- Different regions can have different climates.
What is climate?
- Requires measurements of weather conditions at thousands of locations every day of the year
- observations used to quantify long-term average conditions
Climate varies by latitude
- Solar energy (sun) warms the air, land & water
- impacts temperature
- impacts air movement (wind patterns)
- impacts evaporation
- Earth is round, sun radiation strikes unevenly
- direct @ equator
- more diffuse (spread out) towards poles
- Creates differences in climate across latitudes
- relation north or south of the Earth’s equator
Climate varies by season
- Earth is titled & spinning as it circles sun
- impacts day length
- impacts amount of solar energy
- impacts temperature
- Climate within a latitude change during the year
- dry & wet seasons
- wind and ocean currents
- Seasonal variation smallest at equator
- increases towards poles
Climate varies by latitude
Bodies of water play huge role in climate
- Oceans are heat conveyor belts
- heat/cool air masses
- currents move them
- Impacts climate of land
- water absorbs lot of heat!
Climate patterns distribute life on Earth
- Major zones of vegetation are called biomes
- tropics → desert → tundra
- Biomes are largely defined by temperature and precipitation
- annual averages
- seasonal variation
- Why do areas of N. America, with similar annual averages of climate factors, support either deciduous trees or evergreen trees?
Distribution of terrestrial biomes
What makes a biome a biome?
- Biomes named for:
- Physical features (polar ice)
- Climate features (tropical / temperate)
- Vegetation (grassland / broad-leaf forest)
- Contain organisms adapted for the environment
- animals, plants, fungi, etc
- Boundaries between biomes are not firm
- ecotones: areas of overlap
What makes a biome a biome?
- Biomes are divided into vertical layers
- aboveground & belowground
- each layer has distinct species
- Species composition varies within biomes
- abundance or presence/absence
- Question: Why will different desserts have similar looking but unrelated species of cacti?
Aquatic biomes are also diverse
- Characterized by physical and chemical environment
- fresh vs saltwater
- depth of light penetration
- Oceans cover 3/4 of Earth’s surface
- evaporation fuels rainfall
- algae and bacteria supply O2
- regulate global temperature and wind
- Freshwater biomes linked to terrestrial neighbor
- soil inputs determine chemistry
- related climate
Species distributions: Where and Why?
- Species distributions are part ecology & part evolution
- Why are kangaroos only in Australia?
- Why are different kangaroos in some habitats but not others?
- abiotic factors?
- biotic factors?
Kangaroos evolved in Australia
Dispersal keeps kangaroos in Australia (mostly)
- Dispersal:
- limits the distribution of a species
- Some organisms can disperse widely
- which ones?
- Kangaroos cannot
- humans are unnatural dispersers
- Geographic isolation is key to evolution
Kangaroo species are adapted to climate
Abiotic limitations to Red Kangaroo distribution
Biotic limitations to kangaroo distribution (competition)
Where can a species exist?
